Variable cycle and time rf activation method for film thickness matching in a multi-station deposition system

ABSTRACT

Methods and apparatuses for depositing approximately equal thicknesses of a material on at least two substrates concurrently processed in separate stations of a multi-station deposition apparatus are provided.

INCORPORATION BY REFERENCE

An Application Data Sheet is filed concurrently with this specificationas part of the present application. Each application that the presentapplication claims benefit of or priority to as identified in theconcurrently filed Application Data Sheet is incorporated by referenceherein in its entirety and for all purposes.

BACKGROUND

Some semiconductor manufacturing processes deposit one or more layers ofa material onto a semiconductor substrate or wafer. Integrated circuitfabricators and equipment designers employ various process and apparatusarrangements to produce integrated circuits of uniform quality and withhigh throughput. Material deposition systems such as chemical vapordeposition chambers are operated in different modes, some that emphasizehigh throughput and others that emphasize uniformity. Defining modes ofoperation that optimizes both throughput and uniformity remains achallenge.

SUMMARY

In one embodiment, a method of depositing approximately equalthicknesses of a material on at least two substrates concurrentlyprocessed in separate stations of a multi-station deposition apparatusis provided. The method may include (a) providing a first substrate in afirst station and a second substrate in a second station of thedeposition apparatus, (b) concurrently depositing the material on thefirst substrate in the first station and on the second substrate in thesecond station, wherein deposition conditions in the first and secondstations are substantially the same, but yet produce a thicker layer ofthe material on the first substrate in the first station than on thesecond substrate in the second station, (c) adjusting the depositionconditions in the first station to slow or stop depositing the materialon the first substrate while continuing to deposit the material on thesecond substrate in the second station under the conditions in (b), and(d) completing deposition on the first substrate in the first stationand the second substrate in the second station such that a totalthickness of the material deposited on the first substrate and on thesecond substrate is substantially equal.

In one such embodiment, the deposition conditions may include exposingthe first substrate and the second substrate to a precursor of thematerial.

In further such embodiments, adjusting the deposition conditions mayinclude reducing or stopping flow of the precursor to the first station.

In another embodiment, the deposition conditions may include exposingthe first substrate and the second substrate to a plasma.

In further such embodiments, adjusting the deposition conditions mayinclude reducing or stopping the exposure of the first substrate to theplasma.

In some embodiments, the first wafer may not move from the first stationduring (b) and (c)

In one such embodiment, (b) may include a cyclic repetition of (i)precursor dosing to absorb precursor on the first and second substrates,and (ii) exposing the first and second substrates to plasma to cause theprecursor to react to form the material.

In further such embodiments, (c) may include stopping the precursordosing and/or the plasma exposure in the first station to thereby reducea thickness of the material deposited during the cyclic repetitions,while continuing to conduct the cyclic repetitions on the secondsubstrate in the second station under the conditions in (b).

In other further such embodiments, (c) may include adjusting theduration or power of the plasma in the first station to thereby reduce athickness of the material deposited during the cyclic repetitions, whilecontinuing to conduct the cyclic repetitions on the second substrate inthe second station under the conditions in (b).

In one other embodiment, the method may further include, before orduring (b), analyzing measurement information regarding the relativedeposition rates in the first and second stations, and using themeasurement information to determine how to adjust the depositionconditions in (c).

In further such embodiments, the measurement information may be obtainedduring (b).

In some embodiments, the method may further include, before or during(b), analyzing measurement information regarding physicalcharacteristics of the first substrate and the second substrate, andusing the measurement information to determine how to adjust thedeposition conditions in (c).

In one embodiment, a method of semiconductor deposition for creatingapproximately equal thicknesses of a material on at least two substratesconcurrently processed in separate stations of a multi-stationdeposition apparatus may be provided. The method may include (a)providing a first substrate in a first station and a second substrate ina second station of the deposition apparatus, (b) exposing, at the sametime, the first substrate in the first station and the second substratein the second station to a precursor of the material, (c) activating, atthe same time, a reaction of the precursor on the first substrate in thefirst station and a reaction of the precursor on the second substrate inthe second station, (d) performing (b) and (c) for N1 cycles, each ofthe N1 cycles including depositing a thin film of substantially equalthickness t1 of the material on the first substrate and a thin film ofsubstantially equal thickness t2 of the material on the secondsubstrate, and performing N1 cycles creates a total deposition thicknessT1 of the material on the first substrate and a total depositionthickness T2A of the material on the second substrate, wherein T1 isgreater than T2A, and (e) exposing the second substrate in the secondstation to the precursor and activating a reaction of the precursor onthe second substrate in the second station for N2 cycles, each of the N2cycles includes depositing a thin film of substantially equal thicknesst2 of the material on the second substrate, each of the N2 cyclesincludes the first substrate remaining in the first station and slowingor stopping the deposition of a layer of the material on the firstsubstrate, and performing N1 and N2 cycles creates a total depositionthickness T2 of the material on the second substrate that issubstantially equal to T1.

In one such embodiment, the activating in (c) may include independentlyproviding a plasma in each station for a first plasma time at a firstplasma power, and the activating in (e) may include independentlyproviding a plasma in the second station.

In one further such embodiment, the activating in (e) may includeindependently providing a plasma in the second station for a secondplasma time that is different than the first plasma time, and the thinfilm of substantially equal thickness t2 deposited in each N1 cycle maybe different than the thin film of substantially equal thickness t2deposited in each N2 cycle.

In one other further such embodiment, the activating in (e) may includeindependently providing a plasma in the second station at a secondplasma power level that is different than the first plasma power level,and the thin film of substantially equal thickness t2 deposited in eachN1 cycle may be different than the thin film of substantially equalthickness t2 deposited in each N2 cycle.

In some embodiments, the exposing in (c) may include flowing a precursorfor a first exposure time to the first station and the second station,the exposing in (e) may include flowing a precursor for a secondexposure time to the second station, and the thin film of substantiallyequal thickness t2 deposited in each N1 cycle may be different than thethin film of substantially equal thickness t2 deposited in each N2cycle.

In one embodiment, a multi-station deposition apparatus may be provided.The apparatus may include a vacuum system, a gas delivery system, aprocessing chamber that includes at least two stations, each stationshares the vacuum system and the gas delivery system, and a controllerfor controlling the multi-station deposition apparatus to depositapproximately equal thicknesses of a material on at least two substratesconcurrently processed in separate stations. The controller may includecontrol logic for (a) providing a first substrate in a first station anda second substrate in a second station of the deposition apparatus, (b)concurrently depositing the material on the first substrate in the firststation and on the second substrate in the second station, depositionconditions in the first and second stations are substantially the same,but yet produce a thicker layer of the material on the first substratein the first station than on the second substrate in the second station,(c) adjusting the deposition conditions in the first station to slow orstop depositing the material on the first substrate while continuing todeposit the material on the second substrate in the second station underthe conditions in (b), and (d) completing deposition on the firstsubstrate in the first station and the second substrate in the secondstation such that a total thickness of the material deposited on thefirst substrate and on the second substrate is substantially equal.

In one such embodiment, each station may include a showerhead todistribute a precursor of the material onto the substrate in thatstation, and the gas delivery system may be configured to controldelivery of the precursor of the material to each station.

In one further embodiment, the controller may further include controllogic for independently controlling precursor delivery to each station,and adjusting the deposition conditions in (c) may include reducing orstopping flow of the precursor to the first station.

In one other embodiment, the apparatus may further include a plasmasource configured to independently form and maintain a plasma in eachstation, the controller may further include control logic forindependently forming and maintaining a plasma in each station, and thedeposition conditions in (b) may include exposing the first substrateand the second substrate to the plasma.

In one further embodiment, the controller may further include controllogic for independently controlling a plasma power level in eachstation, and adjusting the deposition conditions in (c) may includereducing or stopping the exposure of the first substrate to the plasma.

In one other further embodiment, the controller may further includecontrol logic for independently controlling a plasma time in eachstation, and adjusting the deposition conditions in (c) may includereducing or stopping the exposure of the first substrate to the plasma.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a substrate processing apparatus for depositing films onsemiconductor substrates using any number of processes.

FIG. 2 depicts an implementation of a multi-station processing tool.

FIG. 3 depicts a flowchart for a first example technique for depositingapproximately equal thicknesses of a material on at least two substratesconcurrently processed in separate stations of a multi-stationdeposition apparatus.

FIG. 4 depicts a graph showing a general relationship between plasmaexposure time and thickness of a material formed by the plasma.

FIG. 5 depicts a flowchart for a second example technique for creatingapproximately equal thicknesses of a material on at least two substratesconcurrently processed in separate stations of a multi-stationdeposition apparatus.

FIG. 6 depicts a chart of an example implementation using feed forwardinformation.

FIG. 7 depicts a graph of measured thicknesses for a four-stationdeposition apparatus for two different deposition processes.

FIG. 8 depicts a flowchart of an example sequence of operations forforming a film of material on a substrate via an atomic layer depositionprocess.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the presented concepts. Thepresented concepts may be practiced without some or all of thesespecific details. In other instances, well known process operations havenot been described in detail so as to not unnecessarily obscure thedescribed concepts. While some concepts will be described in conjunctionwith the specific implementations, it will be understood that theseimplementations are not intended to be limiting.

There are many concepts and implementations described and illustratedherein. While certain features, attributes and advantages of theimplementations discussed herein have been described and illustrated, itshould be understood that many others, as well as different and/orsimilar implementations, features, attributes and advantages of thepresent inventions, are apparent from the description and illustrations.As such, the below implementations are merely some possible examples ofthe present disclosure. They are not intended to be exhaustive or tolimit the disclosure to the precise forms, techniques, materials and/orconfigurations disclosed. Many modifications and variations are possiblein light of this disclosure. It is to be understood that otherimplementations may be utilized and operational changes may be madewithout departing from the scope of the present disclosure. As such, thescope of the disclosure is not limited solely to the description belowbecause the description of the above implementations has been presentedfor the purposes of illustration and description.

Importantly, the present disclosure is neither limited to any singleaspect nor implementation, nor to any single combination and/orpermutation of such aspects and/or implementations. Moreover, each ofthe aspects of the present disclosure, and/or implementations thereof,may be employed alone or in combination with one or more of the otheraspects and/or implementations thereof. For the sake of brevity, many ofthose permutations and combinations will not be discussed and/orillustrated separately herein.

Some semiconductor processes are used to deposit one or more layers of amaterial onto a substrate such as a wafer. When used herein, “wafer” cantypically be interpreted to include other forms of “substrate” such as alarge format display substrate. Examples of such deposition processesinclude chemical vapor deposition (“CVD”), plasma-enhanced CVD(“PECVD”), atomic layer deposition (“ALD”), low pressure CVD, ultra-highCVD, physical vapor deposition (“PVD”), and conformal film deposition(“CFD”).

For instance, some CVD processes may deposit a film on a wafer surfaceby flowing one or more gas reactants into a reactor which form filmprecursors and by-products. The precursors are transported to the wafersurface where they are adsorbed by the wafer, diffused into the wafer,and deposited on the wafer by chemical reactions which also generateby-products that are removed from the surface and from the reactor.

For another example, some deposition processes involve multiple filmdeposition cycles, each producing a “discrete” film thickness. ALD isone such film deposition method, but any technique which puts down thinlayers of film and used in a repeating sequential matter may be viewedas involving multiple cycles of deposition.

As device and features size continue to shrink in the semiconductorindustry, and also as 3D devices structures become more prevalent inintegrated circuit (IC) design, the capability of depositing thinconformal films (films of material having a uniform thickness relativeto the shape of the underlying structure, even if non-planar) continuesto gain importance. ALD is a film forming technique which is well-suitedto the deposition of conformal films due to the fact that a single cycleof ALD only deposits a single thin layer of material, the thicknessbeing limited by the amount of one or more film precursor reactantswhich may adsorb onto the substrate surface (i.e., forming anadsorption-limited layer) prior to the film-forming chemical reactionitself. Multiple “ALD cycles” may then be used to build up a film of thedesired thickness, and since each layer is thin and conformal, theresulting film substantially conforms to the shape of the underlyingdevices structure. In certain embodiments, each ALD cycle includes thefollowing steps:

-   -   1. Exposure of the substrate surface to a first precursor.    -   2. Purge of the reaction chamber in which the substrate is        located.    -   3. Activation of a reaction of the substrate surface, typically        with a plasma and/or a second precursor.    -   4. Purge of the reaction chamber in which the substrate is        located.

The duration of each ALD cycle may typically be less than 25 seconds orless than 10 seconds or less than 5 seconds. The plasma exposure step(or steps) of the ALD cycle may be of a short duration, such as aduration of 1 second or less. FIG. 8 depicts a flowchart of an examplesequence of operations for forming a film of material on a substrate viaan ALD process. As can be seen in FIG. 8, item 1 above corresponds withblock 858, item 2 above corresponds with block 860, item 3 abovecorresponds with block 862, and item 4 above corresponds with block 864;the four blocks are performed for N cycles, after which the process isstopped.

FIG. 1 shows a substrate processing apparatus for depositing films onsemiconductor substrates using any number of processes. The apparatus100 of FIG. 1 has a single processing chamber 102 with a singlesubstrate holder 108 (e.g., a pedestal) in an interior volume which maybe maintained under vacuum by vacuum pump 118. Also fluidically coupledto the chamber for the delivery of (for example) film precursors,carrier and/or purge and/or process gases, secondary reactants, etc. isgas delivery system 101 and showerhead 106. Equipment for generating aplasma within the processing chamber is also shown in FIG. 1. Theapparatus schematically illustrated in FIG. 1 is commonly for performingALD, although it may be adapted for performing other film depositionoperations such as conventional CVD, particularly plasma enhanced CVD.

For simplicity, processing apparatus 100 is depicted as a standaloneprocess station having a process chamber body 102 for maintaining alow-pressure environment. However, it will be appreciated that aplurality of process stations may be included in a common process toolenvironment—e.g., within a common reaction chamber—as described herein.For example, FIG. 2 depicts an implementation of a multi-stationprocessing tool and is discussed in further detail below. Further, itwill be appreciated that, in some implementations, one or more hardwareparameters of processing apparatus 100, including those discussed indetail herein, may be adjusted programmatically by one or more systemcontrollers.

Process station 100 fluidically communicates with gas delivery system101 for delivering process gases, which may include liquids and/orgases, to a distribution showerhead 106. Gas delivery system 101includes a mixing vessel 104 for blending and/or conditioning processgases for delivery to showerhead 106. One or more mixing vessel inletvalves 120 may control introduction of process gases to mixing vessel104.

Some reactants may be stored in liquid form prior to vaporization andsubsequent delivery to the process chamber 102. The implementation ofFIG. 1 includes a vaporization point 103 for vaporizing liquid reactantto be supplied to mixing vessel 104. In some implementations,vaporization point 103 may be a heated liquid injection module. In someother implementations, vaporization point 103 may be a heated vaporizer.In yet other implementations, vaporization point 103 may be eliminatedfrom the process station.

In some implementations, a liquid flow controller (LFC) upstream ofvaporization point 103 may be provided for controlling a mass flow ofliquid for vaporization and delivery to processing chamber 102.

Showerhead 106 distributes process gases and/or reactants (e.g., filmprecursors) toward substrate 112 at the process station, the flow ofwhich is controlled by one or more valves upstream from the showerhead(e.g., valves 120, 120A, 105). In the implementation shown in FIG. 1,substrate 112 is located beneath showerhead 106, and is shown resting ona pedestal 108. Showerhead 106 may have any suitable shape, and may haveany suitable number and arrangement of ports for distributing processesgases to substrate 112. In some implementations with two or morestations, the gas delivery system 101 includes valves or other flowcontrol structures upstream from the showerhead, which can independentlycontrol the flow of process gases and/or reactants to each station suchthat gas may be flowed to one station but not another. Furthermore, thegas delivery system 101 may be configured to independently control theprocess gases and/or reactants delivered to each station in amulti-station apparatus such that the gas composition provided todifferent stations is different; e.g., the partial pressure of a gascomponent may vary between stations at the same time.

A volume 107 is located beneath showerhead 106. In some implementations,pedestal 108 may be raised or lowered to expose substrate 112 to volume107 and/or to vary a volume of volume 107. Optionally, pedestal 108 maybe lowered and/or raised during portions of the deposition process tomodulate process pressure, reactant concentration, etc. within volume107.

In FIG. 1, showerhead 106 and pedestal 108 are electrically connected toRF power supply 114 and matching network 116 for powering a plasma. Insome implementations, the plasma energy may be controlled (e.g., via asystem controller having appropriate machine-readable instructionsand/or control logic) by controlling one or more of a process stationpressure, a gas concentration, an RF source power, an RF sourcefrequency, and a plasma power pulse timing. For example, RF power supply114 and matching network 116 may be operated at any suitable power toform a plasma having a desired composition of radical species. Likewise,RF power supply 114 may provide RF power of any suitable frequency andpower.

In some implementations with two or more stations, the apparatus isconfigured such that the RF power supply 114 and associated componentsignite and sustain a plasma in each station independently. For example,the apparatus may be configured to maintain a plasma in one stationwhile, at the same time, not forming a plasma in another station.Further, the apparatus may be configured to maintain a plasma in twostations, but with different plasma characteristics such as plasmapower, density, composition, duration, etc.

In some implementations, the plasma ignition and maintenance conditionsare controlled with appropriate hardware and/or appropriatemachine-readable instructions in a system controller which may providecontrol instructions via a sequence of input/output control (IOC)instructions. In one example, the instructions for setting plasmaconditions for plasma ignition or maintenance are provided in the formof a plasma activation recipe of a process recipe. In some cases,process recipes may be sequentially arranged, so that all instructionsfor a process are executed concurrently with that process. In someimplementations, instructions for setting one or more plasma parametersmay be included in a recipe preceding a plasma process. For example, afirst recipe may include instructions for setting a flow rate of aninert (e.g., helium) and/or a reactant gas, instructions for setting aplasma generator to a power set point, and time delay instructions forthe first recipe. A second, subsequent recipe may include instructionsfor enabling the plasma generator and time delay instructions for thesecond recipe. A third recipe may include instructions for disabling theplasma generator and time delay instructions for the third recipe. Itwill be appreciated that these recipes may be further subdivided and/oriterated in any suitable way within the scope of the present disclosure.

In some deposition processes, plasma strikes last on the order of a fewseconds or more in duration. In certain implementations describedherein, much shorter plasma strikes may be applied during a processingcycle. These may be on the order of less than 50 milliseconds, with 25milliseconds being a specific example.

As described above, one or more process stations may be included in amulti-station substrate processing tool. FIG. 2 shows an examplemulti-station substrate processing apparatus. Various efficiencies maybe achieved through the use of a multi-station processing apparatus likethat shown in FIG. 2 with respect to equipment cost, operationalexpenses, as well as increased throughput. For instance, a single vacuumpump may be used to create a single high-vacuum environment for all fourprocess stations by evacuating spent process gases, etc. for all fourprocess stations. Depending on the implementation, each process stationmay have its own dedicated showerhead for gas delivery, but may sharethe same gas delivery system. Likewise, certain elements of the plasmagenerator equipment may be shared amongst process stations (e.g., powersupplies), although depending on the implementation, certain aspects maybe process station-specific (for example, if showerheads are used toapply plasma-generating electrical potentials). Once again, it is to beunderstood that such efficiencies may also be achieved to a greater orlesser extent by using more or fewer numbers of process stations perprocessing chamber such as 2, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,or 16, or more process stations per reaction chamber.

The substrate processing apparatus 200 of FIG. 2 employs a singlesubstrate processing chamber 214 that contains multiple substrateprocess stations, each of which may be used to perform processingoperations on a substrate held in a wafer holder, e.g., a pedestal, atthat process station. In this particular implementation, themulti-station substrate processing apparatus 200 is shown having fourprocess stations 201, 202, 203, and 204. Other similar multi-stationprocessing apparatuses may have more or fewer processing stationsdepending on the implementation and, for instance, the desired level ofparallel wafer processing, size/space constraints, cost constraints,etc. Also shown in FIG. 2 are a substrate handler robot 226 and acontroller 250.

As shown in FIG. 2, the multi-station processing tool 200 has asubstrate loading port 220, and a robot 226 configured to movesubstrates from a cassette loaded through a pod 228 through atmosphericport 220, into the processing chamber 214, and onto one of the fourstations 201, 202, 203, or 204.

The depicted processing chamber 214 shown in FIG. 2 provides fourprocess stations, 201, 202, 203, and 204. The RF power is generated atan RF power system 213 and distributed to each of the stations 201, 202,203, and 204. The RF power system may include one or more RF powersources, e.g., a high frequency (HFRF) and a low frequency (LFRF)source, impedance matching modules, and filters. In certainimplementations, the power source may be limited to only the highfrequency or low frequency source. The distribution system of the RFpower system may be symmetric about the reactor and may have highimpedance. This symmetry and impedance result in approximately equalamounts of power being delivered to each station. As stated above, insome implementations the RF power system may be configured toindependently deliver power to each station. For example, RF power maybe delivered simultaneously to stations 201 and 202, and at the sametime not delivered to stations 203 and 204, such that a plasma issimultaneously formed and maintained only in stations 201 and 202.

FIG. 2 also depicts an implementation of a system controller 250employed to control process conditions and hardware states of processtool 200 and its process stations. System controller 250 may include oneor more memory devices 256, one or more mass storage devices 254, andone or more processors 252. Processor 252 may include one or more CPUs,ASICs, general-purpose computer(s) and/or specific purpose computer(s),one or more analog and/or digital input/output connection(s), one ormore stepper motor controller board(s), etc.

In some implementations, system controller 250 controls some or all ofthe operations of process tool 200 including the operations of itsindividual process stations. System controller 250 may executemachine-readable system control instructions 258 on processor 252; thesystem control instructions 258, in some implementations, loaded intomemory device 256 from mass storage device 254. System controlinstructions 258 may include instructions for controlling the timing,mixture of gaseous and liquid reactants, chamber and/or stationpressure, chamber and/or station temperature, wafer temperature, targetpower levels, RF power levels, RF exposure time, substrate pedestal,chuck, and/or susceptor position, plasma formation in each station(which, as discussed above, may include independent plasma formation inone or more stations), flow of gaseous and liquid reactants (which, asstated above, may include independent flow to one or more stations) andother parameters of a particular process performed by process tool 200.These processes may include various types of processes including, butnot limited to, processes related to deposition of film on substrates.System control instructions 258 may be configured in any suitable way.For example, various process tool component subroutines or controlobjects may be written to control operation of the process toolcomponents. System control instructions 258 may be coded in any suitablecomputer readable programming language. In some implementations, systemcontrol instructions 258 are implemented in software, in otherimplementations, the instructions may be implemented in hardware—forexample, hard-coded as logic in an ASIC (application specific integratedcircuit), or, in other implementations, implemented as a combination ofsoftware and hardware.

In some implementations, system control software 258 may includeinput/output control (IOC) instructions for controlling the variousparameters described above. For example, each step of a depositionprocess or processes may include one or more instructions for executionby system controller 250. The instructions for setting processconditions for a primary film deposition process, for example, may beincluded in a corresponding deposition recipe, and likewise for acapping film deposition. In some implementations, the recipes may besequentially arranged, so that all instructions for a process areexecuted concurrently with that process.

Other computer-readable instructions and/or programs stored on massstorage device 254 and/or memory device 256 associated with systemcontroller 250 may be employed in some implementations. Examples ofprograms or sections of programs include a substrate positioningprogram, a process gas control program, a pressure control program, aheater control program, and a plasma control program.

In some implementations, there may be a user interface associated withsystem controller 250. The user interface may include a display screen,graphical software displays of the apparatus and/or process conditions,and user input devices such as pointing devices, keyboards, touchscreens, microphones, etc.

In some implementations, parameters adjusted by system controller 250relate to process conditions. Non-limiting examples include process gascompositions and flow rates, temperatures, pressures, plasma conditions(such as RF bias power levels, frequencies, exposure times), etc.Additionally, the controller may be configured to independently controlconditions in the process stations, e.g., the controller providesinstructions to ignite a plasma in some but not all stations. Theseparameters may be provided to the user in the form of a recipe, whichmay be entered utilizing the user interface.

Signals for monitoring the processes may be provided by analog and/ordigital input connections of system controller 250 from various processtool sensors. The signals for controlling the processes may be output onthe analog and/or digital output connections of process tool 200.Non-limiting examples of process tool sensors that may be monitoredinclude mass flow controllers (MFCs), pressure sensors (such asmanometers), thermocouples, load sensors, OES sensors, metrologyequipment for measuring physical characteristics of wavers in-situ, etc.Appropriately programmed feedback and control algorithms may be usedwith data from these sensors to maintain process conditions.

System controller 250 may provide machine-readable instructions forimplementing deposition processes. The instructions may control avariety of process parameters, such as DC power level, RF bias powerlevel, station-to-station variations such as RF power parametervariations, frequency tuning parameters, pressure, temperature, etc. Theinstructions may control the parameters to operate in-situ deposition offilm stacks according to various implementations described herein.

The system controller will typically include one or more memory devicesand one or more processors configured to execute machine-readableinstructions so that the apparatus will perform operations in accordancewith the processes disclosed herein. Machine-readable, non-transitorymedia containing instructions for controlling operations in accordancewith the substrate doping processes disclosed herein may be coupled tothe system controller.

As mentioned above, processing multiple substrates at multiple processstations within a common substrate processing chamber may increasethroughput by enabling film deposition to proceed in parallel onmultiple substrates while at the same time utilizing common processingequipment between the various stations. For instance, in a four-stationprocess chamber, four substrates placed in four separate stations may beprocessed at the same time. It should be noted that some multi-stationsubstrate processing tools may be utilized to simultaneously processwafers for an equal number of cycles (e.g., for some ALD processes).Given this configuration of process stations and substrate loading andtransferring devices, a variety of process sequences are possible whichallow film deposition—say, for instance, N cycles of film deposition foran ALD process or an equal exposure duration for a CVD process—to occurin parallel (e.g., simultaneously) across multiple substrates.

Approaches to achieving consistent film deposition across differentsubstrates include indexing a substrate through multiple processstations within the processing chamber over the course of a depositionprocess—i.e., for each substrate, some portion of its film is depositedat one station, and some portion at one or more other processingstations. This may result in an averaging-out of any systematicdifference in deposition occurring at the different stations. Again,this processing mode may be used for any type of deposition processincluding, for instance, CVD and ALD. For example, in an ALD process forwhich a total of N cycles are to be performed on four wafers in afour-station processing chamber, N/4 cycles may be performed on eachwafer in each station, with each wafer being transported to a differentstation after the completion of each of the N/4 cycles. On the otherhand, some other implementations of this approach may not perform anequal number of cycles on each wafer. For another example, in an ALDprocess for which a total of N cycles are to be performed on four wafersin a four-station processing chamber, N×⅖ cycles may be performed oneach wafer in the station in which each wafer is initially placed,followed by N/5 cycles performed each wafer in the other three remainingstations. By way of illustration, 500 total deposition cycles may beperformed on wafers 1, 2, 3, and 4, which are initially placed instations 201, 202, 203, and 204, respectively. 200 cycles are performedon wafer 1 in station 201, after which wafer 1 is then transferred tostations 202, 203, and 204 where 100 cycles are performed on wafer 1 ineach of these stations, respectively, thereby totaling 500 total cycles.The same approach is applied to wafers 2, 3, and 4.

This type of “sequential mode” processing or “sequential processing” isbeneficial in the sense that each wafer sees a different station whichmay average-out some of the systematic differences in depositionoccurring at the different stations. However, other characteristics ofthis mode of operation make it less appealing. For example, someimplementations of sequential mode involve a great deal of substrateloading/unloading, opening/closing of processing chamber port 220. Insome modes of operation, for a substrate to receive its allotted Ndepositions over the 4 stations, the processing chamber has to be openedand closed for loading/unloading operations 4 times, each timeaccompanied by restoration of the environment on chamber's interior backto deposition-appropriate environmental conditions (e.g., temperature,pressure, flow rates, etc.). “Static mode,” when using one station forloading operations, may involve the same amount of indexing—using 90degree transfer rotations of a cassette on which the wafers are locatedwithin the process chamber—to get 4 wafers into position for deposition,but the chamber is only opened and closed once since in static mode nointervening depositions are performed between the transfer rotations.Thus, loading of all four wafers (one by one) into the multi-stationchamber prior to deposition is also possible. Even when the chamberremains closed and the internal pressure remains relatively static, theindexing of wafers from one station to the next delays processing.

Another process sequence, referred to herein as “fixed mode” involves noindexing. In fixed mode, using the example of FIG. 2, the chamber isopened via port 220, wafers are loaded at all four stations, the chamberis closed, N deposition cycles are performed on all four wafers inparallel and simultaneously, the deposition cycles conclude, the chamberis opened, and the four wafers are removed. In other words, eachsubstrate receives its film deposition entirely (all N cycles) at one ofthe four processing stations. This fixed mode processing may be used forany type of deposition process including, for example, CVD and ALD.Fixed mode processing does not have the delay associated with indexingin other modes, so deposition throughput is higher. However, this modemay not always achieve consistent film deposition between the differentsubstrates due to process mismatch between the different stations. Forinstance, the process conditions in one station may not exactly matchthe process conditions in another station, such as different RFfrequencies between stations, which may result in a wafer processed inthe one station having different properties than a wafer processed inanother station. The mismatch between wafers may include, for example,differences in average film thickness, uniformity over the face ofwafer, physical properties, chemical properties, and optical properties.

Techniques for improving the wafer mismatch between stations, i.e.achieving more consistent film deposition across different substrates,in a multi-station process chamber include designing the semiconductorprocessing equipment in a way that minimizes the differences in processconditions between stations. For example, as noted above,station-to-station thickness matching is a problem in multi-stationprocess chambers and this station-to-station thickness may vary becauseof differences in numerous process conditions between stations, such asgas and/or chemistry delivery, RF power delivered to each station,temperature of each station, pumping within the chamber and/or eachstation, hardware settings (e.g., placement and function of the stationhardware), and the physical environment within the chamber. Aspects ofthe multi-station process chamber may be designed and/or built tominimize the differences of these process conditions between eachstation (e.g., identical temperature profiles at each station), but suchdesign in complex and it is nearly impossible to reduce them completely.

Another technique to improve the wafer mismatch between stations in amulti-station process chamber includes adjusting one or more processconditions at one or more stations. However, most process conditions ina deposition process are typically dependent upon one another such thatif process condition A is adjusted to compensate for the difference inprocess condition B, such adjustment may unintentionally impact theeffects of process condition C. For example, the temperature in one ormore stations may be adjusted to improve thickness-matching betweenstations, but this change in temperature may also impact film stress.Therefore, adjusting one or more process conditions at one or morestations is a very complex optimization problem that involves highlycross-correlated variables.

As mentioned above, station-to-station thickness matching can be aproblem in multi-station process chambers operated in fixed mode. Theinventors have determined that station-to-station thickness matching(and other forms of uniformity) may be improved by operating one or morestations normally to deposit a layer of material on a wafer in onestation, while simultaneously slowing or stopping the normal operationof one or more other stations such that deposition of a layer on anotherwafer in the one or more other stations of the multi-station processchamber is slowed or stopped. As discussed below, as an alternative toslowing or stopping the normal operations in one or more stations, theprocess may simply adjust deposition conditions in those stations, whilemaintaining normal conditions in the other stations. Examples ofdeposition conditions that may be adjusted to provide differentconditions in different stations include, among other things, plasmaignition timing, plasma power, duration of the plasma, flow of processgases (e.g., reactant and/or precursor), and partial pressure of processgases. The apparatuses and techniques in this disclosure may apply toany deposition processes, including those described above, such as CVD,PECVD, ALD, and ECD.

FIG. 3 depicts a flowchart for a first example technique for depositingapproximately equal thicknesses of a material on at least two substratesconcurrently processed in separate stations of a multi-stationdeposition apparatus. Such deposition may be performed by, for instance,CVD or ALD. Although this first example illustrates a technique thatinvolves two stations, such technique may be applied to a multi-stationdeposition apparatus with more than two stations, including theapparatuses described above with respect to FIGS. 1 and 2. In block 340of FIG. 3, substrates are provided into the stations of a multi-stationdeposition apparatus. A first substrate may be provided into a firststation and a second substrate may be provided into a second station. Asdiscussed above with reference to FIG. 2, the substrates may be placedinto the stations by a substrate handler robot.

In block 342 of FIG. 3, a material is concurrently deposited on thefirst substrate in the first station and on the second substrate in thesecond station. As stated, this deposition occurs concurrently, i.e.,simultaneously or in parallel, in the stations such that the depositionis occurring on first substrate in the first station at the same time asthe deposition on the second substrate in the second station. Theconcurrent deposition in block 342 may be a single CVD depositionprocess, a single deposition cycle in a cyclic deposition process likeALD, or the total deposition process of a cyclic process. During suchconcurrent deposition, the deposition conditions in the first and secondstations may be substantially the same; e.g., the control system setsparameters intended to produce identical (or nearly identical)conditions in the stations. For certain process parameters (e.g., plasmapower, process gas flow rate), the parameters in the different stationsmay be within a few percent, e.g., within +/−5%, of each other. Asdiscussed above, attempts may be made to create identical processconditions in each station but one or more process conditions acrossstations often do not match exactly. These deposition conditions mayinclude, for example and as noted above, temperature of a pedestal ineach station, partial pressure of a gas flowed into each station, localgas flow conditions, pressure in the chamber, plasma power in eachstation, plasma frequency, and plasma formation duration in each station(for depositions that involve plasma). As a result, the concurrentdeposition may produce a thicker layer of the material on the firstsubstrate in the first station than on the second substrate in thesecond station despite efforts to produce equal layers of the materialon each substrate. For example, in an ALD process, the thicker layer ofthe material may be the total thickness of the material deposited on thesubstrate after performing N cycles, or it could be the thickness of thematerial after a single cycle.

Determining that two or more stations of a chamber deposit material todifferent thicknesses may be accomplished by various techniques. It maybe inferred from device performance or measured directly. As understoodby those of skill in the art, measuring the difference of material layerthickness between two substrates can be performed by any number oftechniques including any known metrology technique, such asreflectometry, various microscopies, etc. Because the depositedthicknesses produced in each station may not typically vary betweendeposition processes until after a certain period of time or a certainnumber of deposition cycles, these measured thicknesses may beconsidered the thicknesses consistently produced by each station foreach process, which may be stored in a memory and/or used for lateraspects of the technique, as discussed below. In another example, thethickness of the layer of material on each substrate may be measured insitu, i.e., while a wafer is in the station and/or chamber before,during, and/or after the deposition process.

In block 344, one or more adjustments are made to the depositionconditions in the first station to slow or stop deposition of thematerial on the first substrate, while the apparatus continues todeposit the material on the second substrate in the second station underthe conditions in block 342. Each adjustment of each depositioncondition that is adjusted may depend on numerous factors, including thedeposition process being utilized as well as the thickness of thematerial that is to be deposited in each station, if any. Theadjustments may, for example, include reducing or stopping the flow ofreactant, e.g., precursor, into the first station. For instance, in aCVD process that began deposition on the two substrates using aparticular set of substantially identical initial deposition conditions,the adjustment may be to stop the flow of a reactant into the firststation in order to stop and/or slow the deposition in the first stationwhile the deposition conditions in the second station may continue underthe initial deposition conditions. In another example, the adjustment ina cyclic deposition process, such as ALD, according to initial,substantially identical deposition conditions may be to stop the flow ofprecursor to the first station for an adsorption stage of one cycle ofthe process such that no material is deposited on the first substrateduring that one cycle, but during that same one cycle, the precursor isflowed to the second station according to the initial depositionconditions such that deposition occurs in the second station.

As noted above, in some embodiments, the adjustment may be to change thedeposition conditions in the first station in order to change thecharacteristics of the layer produced by that deposition process. Thischange in characteristics may be considered a stopping or slowing of thedeposition process.

For deposition processes using plasma exposure in the first and secondstations, adjustment may be made to the plasma conditions in the firststation. For instance, similar to the precursor flow, the adjustment inblock 344 may be to reduce or stop the exposure of the first substrateto the plasma which may in turn slow or stop the deposition process onthe first substrate. This adjustment may be achieved by, among otherthings, stopping the formation of the plasma in the first station,changing the plasma frequency, changing the power level of the plasma inthe first station, and/or changing the time for which the plasma isformed in the first station. In an ALD process, the adjustments may bemade from one cycle to the next. For example, a plasma may be ignited ineach of 100 cycles and then not ignited for each of thirteen cycles. Inother processes that are inherently non-cyclic, the adjustments are madeat a particular point in the deposition process without regard fordefined process transitions. For example, in a PECVD process, the plasmaexposure in the first station may be stopped after a defined durationwhile the plasma exposure in the second station continues under theinitial deposition conditions. As an alternative to simply turning poweroff, other plasma conditions may be adjusted to tune the depositionrate. For instance, the plasma power level in the first station may bereduced in order to slow the deposition process in the first station andthe plasma power level in the second station may continue under theinitial deposition conditions.

Regarding adjustment of the time for which the plasma is formed in thefirst station, such adjustment may be an increase or decrease of thattime which may in turn increase or decrease the thickness of the layerof material. FIG. 4 depicts a graph showing a general relationshipbetween plasma exposure time and thickness of a material formed by theplasma. As can be seen, the thickness of the layer initially increasesas the time of plasma exposure increases, after which a maximumthickness is reached, but as plasma exposure continues after thatmaximum is reached, the layer is caused to densify and thereforedecrease in thickness. Accordingly, this relationship between time ofplasma exposure and thickness of the layer may be used in the adjustmentof the deposition conditions in order to change the deposition of thewafer in the first station such that, for example, the deposition rateof the layer in the first station may be “reduced”, i.e. the thicknessis decreased by additional exposure time to the plasma.

Referring back to FIG. 3, in some implementations block 342 may includea cyclic repetition of (i) precursor dosing to absorb precursor on thefirst and second substrates, and (ii) exposing the first and secondsubstrates to plasma to cause the precursor to react to form thematerial. Such a cyclic repetition may be an ALD process as describedherein and shown, for example, in FIG. 8. In some such implementations,after a certain number of cyclic depositions, an overall thickness ofthe layer of the material on the first wafer may be greater than theoverall thickness of the layer of the material on the second wafer, asnoted above with block 342. Therefore, in block 344, adjustments to thedeposition conditions of one or more cycles in the first station may bemade. In some implementations, these adjustments may include stoppingthe precursor dosing and/or the plasma exposure in the first station inorder to reduce the thickness of the material deposited during thecyclic repetitions, while continuing to conduct the cyclic repetitionson the second substrate in the second station under the conditions inblock 342. As used herein “reduce” may be a layer having a reduced ordecreased thickness, or may be a layer having no thickness, i.e., nolayer is produced during the cycles for which the adjustments are made.In some other implementations, these adjustments may include changingthe duration of plasma exposure or power of the plasma in the firststation in order to reduce the thickness of the material depositedduring the cyclic repetitions, while continuing to conduct the cyclicrepetitions on the second substrate in the second station under theconditions in block 342. Like above, this reduction may include a layerhaving a reduced thickness or that no layer is produced during thecycles for which the adjustments are made.

In some implementations, the first wafer does not move from the firststation during blocks 342 and 344. Therefore, as the deposition iscontinued in the second station under the deposition conditions, thefirst wafer remains in the first station. For instance, theseimplementations may be considered a “fixed mode”.

In block 346, the deposition may be completed on the first substrate inthe first station and the second substrate in the second station suchthat a total thickness of the material deposited on the first substrateand on the second substrate is substantially equal for purposes of theperformance of the resulting integrated circuit or other fabricateddevice. The adjustment(s) in block 344 enable the deposition of thelayer of material on the second substrate in the second station toincrease while the deposition on the first wafer is either stopped,slowed, or otherwise changed in order to cause the thickness of thelayer of material on the second substrate to become substantially equalto the thickness of the layer of material on the first substrate by theend of the total deposition process.

It should be noted that the adjustment of the deposition conditions mayoccur at any point during the technique, such as at the beginning,middle, end, or interspersed throughout the deposition process. Forinstance, in an ALD process that includes 500 concurrent depositioncycles in the first and second stations, the adjustment of block 344 maybe made after the 500 cycles such that for N deposition cycles after allthe 500 cycles, no deposition occurs on the first wafer but depositionof the layer of material does occur on the second wafer in the secondstation for the N cycles.

FIG. 5 depicts a flowchart for a second example technique for creatingapproximately equal thicknesses of a material on at least two substratesconcurrently processed in separate stations of a multi-stationdeposition apparatus. As described herein, the second example techniquemay be used for cyclic deposition processes such as ALD or as depictedin FIG. 8. Block 548 may be the same as block 340 of FIG. 3 as discussedabove, which provides a first substrate in a first station and a secondsubstrate in a second station of the deposition apparatus. As also notedabove with FIG. 3, the second example technique may be applied to amulti-station deposition apparatus having more than two stations andusing the apparatus described herein, such as with respect to FIGS. 1and 2. In block 550, the first substrate and the second substrate areexposed, at the same time (or substantially the same time), to aprecursor of the material. This block may be considered a “dose” phaseof a cyclic deposition process, such as block 858 in FIG. 8 for an ALDprocess. This exposure, or dose, occurs at the same time in each stationsuch that the precursor flows into each station at substantially thesame time for substantially the same duration, e.g., identical to withinabout +/−5% of each other. Although not depicted in FIG. 5, in someimplementations a purge step may occur after block 550 and before block552, as described above with respect to ALD processes and shown in block860 of FIG. 8.

In block 552, the reaction of the precursor on the first substrate inthe first station and on the second substrate in the second station isactivated. In some implementations, this activation is performedthermally upon contact with a reactant, such as a reactant gas, while inother implementations it is performed by exposure to a plasma. As withblock 550, the activation in each station occurs at the same time, orsubstantially the same time (e.g., within about +/−5% of each other).For instance, if the activation is with a plasma, then the activation ofblock 552 is performed by forming the plasma at substantially the sametime in each station for substantially the same duration. Additionally,the deposition conditions of such activation may be substantially equalin each station. The activation of the reaction of the precursor causes,at least in part, the formation of the layer of the material on eachsubstrate.

Block 554 provides that blocks 550 and 552 are performed for N1 cycles.In each of the N1 cycles, a thin film of substantially equal thicknesst1 of the material may be deposited on the first substrate and a thinfilm of substantially equal thickness t2 of the material may bedeposited on the second substrate. Additionally, performing the N1cycles may create a total deposition thickness T1 of the material on thefirst substrate and a total deposition thickness T2A of the material onthe second substrate. In some implementations, T1 is greater than T2A,which is similar to the first technique of FIG. 3.

Block 556 includes exposing the second substrate in the second stationto the precursor and activating a reaction of the precursor on thesecond substrate in the second station for N2 cycles. Each of the N2cycles may include depositing a thin film of substantially equalthickness t2 of the material on the second substrate. In each of the N2cycles, the first substrate may remain in the first station and thedeposition of a layer of the material on the first substrate may bestopped or slowed. Performing N2 cycles may create a total depositionthickness T2B and performing N1 and N2 cycles on the second substratecreates a total deposition thickness T2 (e.g., T2A+T2B) such that T2 issubstantially equal to T1. In some implementations, T2B maysubstantially equal to t2, which may occur when N2 cycles is one cycle.For example, in an ALD process utilizing plasma to activate thereactions, each N2 cycle of block 556 may include exposing the secondsubstrate in the second station with the precursor, forming a plasma inthe second station to activate the reaction of the precursor on thesecond substrate, and at the same time not forming a plasma in the firststation such that no deposition of the layer of the material may occuron the first substrate. In some implementations, block 556 may alsoinclude exposing the first substrate in the first station to theprecursor, but not activating the reaction of the precursor on the firstsubstrate.

Although FIG. 5 includes block 556 at the bottom of the Figure, block556 may be performed at any time throughout the entire depositionprocess. For instance, block 556 may be performed before blocks 550, 552and 554. In another instance, the N2 cycles of block 556 may be brokenup and performed at different times throughout the N1 cycles. Forexample, for a deposition process involving 500 N1 cycles and 100 N2cycles, the cycle order may be as follows: 100 N1 cycles, then 50 N2cycles, then 200 N1 cycles, then 50 N2 cycles, and then 200 N1 cycles.

In some implementations, as discussed herein below, adjustments may bemade to the deposition conditions of the first and/or second stationsfor each of the N2 cycles. For example, in some implementations of thesecond example technique for creating approximately equal thicknesses ofa material on at least two substrates concurrently processed in separatestations of a multi-station deposition apparatus depicted in FIG. 5, theactivation of the reaction of the precursor may be performed by aplasma. In such implementations, a plasma may be independently provided,e.g., ignited and controlled, in each station such that the plasma maybe formed in one station while at the same time the plasma may not beformed in another station. In block 552, the activation may includeindependently providing the plasma to each station for a first plasmatime and at a first plasma power. The first plasma time, i.e., durationfor which the plasma is formed in the station, may vary depending on thedeposition process involved, but may be 1 second or less. The firstplasma power may be the power at which the plasma is generated, and maybe correlated with RF power and/or RF frequency delivered to eachstation.

In block 556, the activation of the reaction of the precursor in thesecond station may include independently igniting and/or controlling aplasma in the second station. At the same time, the plasma may not beprovided to the first station, or the plasma may be provided to thefirst station in such a way as to slow the deposition of the layer ofmaterial on the first substrate.

In some implementations, the activating in block 556 may includeproviding the plasma in the second station for a second plasma time thatis different than the first plasma time. As discussed above withreference to FIG. 4, the duration over which a plasma is formed in eachN2 cycle may cause the thickness of the layer of material deposited onthe second wafer to be less or more than the thickness of the layer ofmaterial deposited in each N1 cycle of block 554. Therefore, the thinfilm of equal thickness t2 deposited in each N1 cycle of block 554 maybe different than, e.g., less than or greater than, the thin film ofequal thickness t2 deposited in each N2 cycle. The ability to producefilms of two different thicknesses per cycle in and across stationsenhances the ability to match station-to-station thickness.

In some implementations, the activating in block 556 may includeproviding the plasma in the second station at a second plasma powerlevel that is different than the first plasma power level. Similar toabove, the different power level in each N2 cycle may cause thethickness of the layer of material deposited on the second wafer to beless or more than the thickness of the layer of material deposited ineach N1 cycle of block 554. Accordingly, the thin film of equalthickness t2 deposited in each N1 cycle of block 554 may be greater thanor less than the thin film of equal thickness t2 deposited in each N2cycle.

In some implementations, the exposure of block 550 may include flowing aprecursor for a first exposure time to the first station and the secondstation. Additionally, the exposure in block 556 may include flowing aprecursor for a second exposure time to the second station. As with thediffering plasma power and plasma duration, exposing the secondsubstrate to the precursor for the second exposure time may cause thedeposition of a layer of the material in each N2 cycle that may have athickness more than or less than the thickness of the layer of materialdeposited in each N1 cycle. For instance, the first exposure time may bea time that enables maximum adsorption of the precursor and the secondexposure time may be 25% less than the first exposure time, which maythus cause the thickness of the layer deposited as a result of the firstexposure time to be greater than the thickness of the layer deposited asa result of the second exposure time.

In some implementations, the exposure of block 550 may include flowing aprecursor with a first partial pressure to the first station and thesecond station. Additionally, the exposure in block 556 may includeflowing a precursor with a second partial pressure to the secondstation. As with the differing plasma power and plasma duration,exposing the second substrate to the precursor with the second partialpressure may deposit a layer of the material in each N2 cycle that mayhave a thickness more or less than the thickness of the layer ofmaterial deposited in each N1 cycle.

Accordingly, the permissible implementations of the first and/or secondexample techniques for creating approximately equal thicknesses of amaterial on at least two substrates concurrently processed, using cyclicdeposition processes, in separate stations of a multi-station depositionapparatus discussed herein may increase the overall thickness of thelayer of the material deposited on the second substrate by, at least:(i) the deposition of additional thin films of substantially equalthickness t2 of the material on the second substrate for N2 cyclesaccording to the deposition conditions of the N1 cycles such that thethin film thickness t2 deposited in each of the N1 cycles and each ofthe N2 cycles are substantially equal, and/or (ii) the deposition ofadditional thin films of substantially equal thickness t2 of thematerial on the second substrate for N2 cycles according to depositionconditions, e.g. different plasma power or duration, that are differentthan the deposition conditions of the N1 cycles such that the thin filmthickness t2 deposited in each of the N1 cycles is different that thethin film thickness t2 deposited in each of the N2 cycles.

In some implementations of the first and/or second example techniquesfor creating approximately equal thicknesses of a material on at leasttwo substrates concurrently processed in separate stations of amulti-station deposition apparatus discussed herein, information, suchas measurement data, about physical characteristics that exist on thewafers in the multi-station deposition apparatus for deposition and/orregarding the relative deposition rates in the first and second stationsmay be analyzed and/or used to determine the optimal adjustment oradjustments to the depositions conditions in the second station. In somesuch implementations, for instance, such measurement information may be“feed forward” measurement information, in some other suchimplementations, for example, such information may be “feedback”measurement information, and in some implementations, such measurementinformation includes both “feed forward” and “feedback” measurementinformation.

In some implementations using “feed forward” measurement information,information, such as information about physical characteristics thatexist on the wafers in the multi-station deposition apparatus fordeposition and/or regarding the relative deposition rates in the firstand second stations, may be obtained and/or known before depositionoccurs on the wafer, which may include before the wafer is placed in themulti-station deposition apparatus for deposition or after the wafer isplaced in the multi-station deposition apparatus but before depositionoccurs. For example, the “feed forward” measurement information may bemeasurement data of each wafer that is obtained by metrology equipment,e.g., in situ or in line, which may be obtained before and/or after thewafer has been placed in the multi-station deposition apparatus. This“feed forward” measurement information may be sent directly to themulti-station deposition apparatus controller that includes controllogic for determining the appropriate adjustments for each of the N2deposition cycles. The “feed forward” measurement information may alsobe provided to a user who may then input the appropriate adjustmentsinto the multi-station deposition apparatus, such as to the controllerthrough the user interface. Such adjustments may be those adjustmentsdiscussed herein, including plasma power, plasma duration, and numbersof N2 cycles.

For example, wafers may be provided into the multi-station depositionapparatus after having been processed in some other fashion, such as aprevious etching process. In such example, known data (e.g., measurementdata obtained from in-situ, in-line, or previous measurements asdescribed above) of the physical characteristics of the wafer to beplaced in and processed by the multi-station deposition apparatus fromthe previous etching process may be fed forward to determine the optimaldeposition conditions to appropriately deposit material and thus matchthe individual features on the wafer in the second station. FIG. 6depicts a chart of an example implementation using feed forwardinformation. The example implementation is for a multi-stationdeposition apparatus with stations 1-4 and wafers 1-4 placed in stations1-4, respectively. The four wafers have been previously etched such thata critical dimension (“CD”), i.e. a resulting distance between each gapformed by the etch process, is known for each wafer prior to thedeposition process and as can be seen, the incoming, pre-deposition CDfor each wafer varies. Here, an ALD process is desired to depositmaterial into the etched gaps such that the final CD is less than the CDimmediately after etching. However, because of the CD variations afterthe etch process, a uniform ALD deposition may cause the variations toremain after the ALD depositions. For instance, a uniform deposition of100 Å to wafers 1,2,3, and 4 would create an output CD of 220 Å, 222 Å,224 Å, and 226 Å, respectively.

Utilizing the “feed forward” measurement information, the depositionconditions in one or more of the four stations may be adjusted such thateach station deposits a layer that causes the final CD to be the desiredCD of 220 Å. In FIG. 6, for example, deposition conditions in station 2may be adjusted such that the final deposited thickness on wafer 2 is101 Å. Such adjustments may be, for example, an additional cycle or acycle with a different plasma power such that a total layer thickness of101 Å is deposited on wafer 2. Similar adjustments may be made to allfour wafers, as can be seen in FIG. 6, such that each final CD is thedesired 220 Å.

In some implementations using “feedback” measurement information, suchas information about physical characteristics that exist on the wafersin the multi-station deposition apparatus for deposition and/orregarding the relative deposition rates in the first and secondstations, may be obtained and/or known during and/or after at least somedeposition has occurred on a wafer. In such implementations, themulti-station deposition apparatus is configured to obtain suchinformation, which may include the use of in situ metrology equipmentsuch as that described herein. For instance, this “feedback” informationmay be obtained during and/or after, the concurrent deposition of thematerial on the first substrate in the first station and on the secondsubstrate in the second station of the first technique of block 342 ofFIG. 3. Additionally, during this block 342, “feedback” measurementinformation regarding the relative deposition rates in the first andsecond stations may be obtained, analyzed, and used to determine how toadjust the deposition conditions, as discussed herein. Similar to above,this “feedback” measurement information may be sent directly to themulti-station deposition apparatus controller that includes controllogic for analyzing it and determining the appropriate adjustments tothe deposition conditions or to a user.

Some embodiments of the present disclosure include a multi-stationdeposition apparatus. Such an apparatus may include some or all of theparts of the apparatuses described hereinabove, such as with respect toFIGS. 1 and 2. In some such embodiments, the multi-station apparatus mayinclude a vacuum system (which may include vacuum pump 118 of FIG. 1), aprecursor delivery system (which, for instance, may be configuredsimilar to gas delivery system 101), a processing chamber (similar toprocess chamber 102) that includes at least two stations and eachstation may share the vacuum system and the precursor delivery system.The apparatus may also include a controller for controlling themulti-station deposition apparatus, such as the controller describedabove with respect to controller 250 of FIG. 2.

In some embodiments, the controller may control the multi-stationdeposition apparatus to deposit approximately equal thicknesses of amaterial on at least two substrates concurrently processed in separatestations and the controller may comprise control logic for implementingat least part of the techniques described herein with respect to FIGS. 3and 5. For instance, the controller may comprise control logic for: (a)providing a first substrate in a first station and a second substrate ina second station of the deposition apparatus, (b) concurrentlydepositing the material on the first substrate in the first station andon the second substrate in the second station, wherein depositionconditions in the first and second stations are substantially the same,but yet produce a thicker layer of the material on the first substratein the first station than on the second substrate in the second station,(c) adjusting the deposition conditions in the first station to slow orstop depositing the material on the first substrate while continuing todeposit the material on the second substrate in the second station underthe conditions in (b), and (c) completing deposition on the firstsubstrate in the first station and the second substrate in the secondstation such that a total thickness of the material deposited on thefirst substrate and on the second substrate is substantially equal.

In some embodiments, each station of the apparatus may include ashowerhead that is configured to distribute a precursor of the materialonto the substrate in that station (such as showerhead 106), and theprecursor delivery system is configured to control delivery of theprecursor of the material to each station. In some such embodiments, thecontroller may also include control logic for independently controllingprecursor delivery to each station, and adjusting the depositionconditions in (c), above, includes reducing or stopping flow of theprecursor to the first station.

In some embodiments, the apparatus may include a plasma source that isconfigured to independently form and maintain a plasma in each station(such as that described with respect to FIGS. 1 and 2). In some suchembodiments, the controller may include control logic for independentlyforming and maintaining a plasma in each station, and the depositionconditions in (b) may include exposing the first substrate and thesecond substrate to the plasma. In some such embodiments, the controllermay also include control logic for independently controlling a plasmapower level in each station, and the adjusting the deposition conditionsin (c) includes reducing or stopping the exposure of the first substrateto the plasma. In some other such embodiments, the controller may alsoinclude control logic for independently controlling a plasma time ineach station, and adjusting the deposition conditions in (c) comprisesreducing or stopping the exposure of the first substrate to the plasma.

The present inventors utilized techniques and apparatus disclosed hereinto improve thickness matching across stations in a multi-stationdeposition apparatus as shown in FIG. 7. FIG. 7 depicts a graph ofmeasured thicknesses for a four-station deposition apparatus for twodifferent deposition processes. This may be similar to the apparatusdiscussed hereinabove. The y-axis represents the thickness in Angstroms(Å) and the x-axis indicates a processed wafer in each of the fourstations. Each circle represents a total wafer thickness deposited afterperforming the number of cycles indicated above or below each circle.For the first deposition process, its data is shown with a dashed-dottedline, the inventors performed a cyclic deposition process for 579 cyclesconcurrently at each of the four stations which deposited layers of amaterial on each substrate such that the total thickness on eachsubstrate does not match the other substrates' total thicknesses. As canbe seen, the total thickness of material on the wafer in station 1 isapproximately 787 Å, the total thickness of material on the wafer instation 2 is a little greater than 788 Å, the total thickness ofmaterial on the wafer in station 3 is between 791 Å and 792 Å, and thetotal thickness of material on the wafer in station 4 is approximately787 Å. This is a total deviation of approximately 4.6 Å.

For the second deposition process, its data shown with a solid line, theinventors performed cyclic deposition processes using the techniques andthe apparatus disclosed herein to achieve more consistent thicknessmatching between the stations. Here, the inventors began by performingconcurrent cyclic depositions in all four stations for 579 cycles.However, while all four wafers remained in each station, respectively,the inventors performed additional, independent deposition cycles on thewafer in the other stations in order to achieve thickness across thestations of approximately 791 Å. As can be seen, station 1 received fouradditional deposition cycles to total 583 total cycles and a thicknessof approximately 791 Å, station 2 received two additional cycles tototal 581 total cycles and a thickness of approximately 791 Å, station 3received no additional cycles and had a total thickness of approximately791 Å, and station 4 received three additional cycles to total 582 totalcycles and a thickness of approximately 791 Å.

In order to perform such additional deposition cycles and maximizethroughput while minimizing costs and material usage, after performingthe initial 579 cycles in all four stations, the inventors performed twoadditional deposition cycles concurrently in stations 1, 2, and 4,thereby totaling 581 total cycles in each of these stations,respectively, while the wafer in station 3 remained in its station andno additional deposition cycles were performed in station 3. Afterwards,one additional deposition cycle was performed concurrently on bothstations 1 and 4, thereby totaling 582 total cycles in each of thesestations, respectively, while the wafers in stations 2 and 3 remained intheir respective stations and no additional deposition cycles wereperformed in stations 2 and 3. Finally, one additional deposition cyclewas performed in station 1, thus totaling 583 cycles in that station,while the wafers in stations 2, 3, and 4 remained in their respectivestations and no additional deposition cycles were performed in stations2, 3, or 4. It should be noted that in all the deposition cycles of FIG.7, the same deposition conditions were used for each deposition cycle.The thickness variation between the stations in FIG. 6 was reduced fromapproximately 4.6 Å in the first data set to approximately 0.4 Å for thesecond set, which is an approximate 10-fold reduction. In otherembodiments, as discussed above, these additional cycles on eachrespective station may be performed at any point during the entiredeposition process, such as at the beginning of the process.

Unless the context of this disclosure clearly requires otherwise,throughout the description and the claims, the words “comprise,”“comprising,” and the like are to be construed in an inclusive sense asopposed to an exclusive or exhaustive sense; that is to say, in a senseof “including, but not limited to.” Words using the singular or pluralnumber also generally include the plural or singular numberrespectively. When the word “or” is used in reference to a list of twoor more items, that word covers all of the following interpretations ofthe word: any of the items in the list, all of the items in the list,and any combination of the items in the list. The term “implementation”refers to implementations of techniques and methods described herein, aswell as to physical objects that embody the structures and/orincorporate the techniques and/or methods described herein.

What is claimed is:
 1. A multi-station deposition apparatus, theapparatus comprising: a vacuum system; a gas delivery system; aprocessing chamber that includes at least two stations, wherein eachstation shares the vacuum system and the gas delivery system; and acontroller for controlling the multi-station deposition apparatus todeposit approximately equal thicknesses of a material on at least twosubstrates concurrently processed in separate stations, the controllercomprising control logic for: (a) providing a first substrate in a firststation and a second substrate in a second station of the depositionapparatus, (b) concurrently depositing the material on the firstsubstrate in the first station and on the second substrate in the secondstation, wherein deposition conditions in the first and second stationsare substantially the same, but yet produce a thicker layer of thematerial on the first substrate in the first station than on the secondsubstrate in the second station, (c) adjusting the deposition conditionsin the first station to slow or stop depositing the material on thefirst substrate while continuing to deposit the material on the secondsubstrate in the second station under the conditions in (b), and (d)completing deposition on the first substrate in the first station andthe second substrate in the second station such that a total thicknessof the material deposited on the first substrate and on the secondsubstrate is substantially equal.
 2. The apparatus of claim 1, wherein:each station comprises a showerhead to distribute a precursor of thematerial onto the substrate in that station, and the gas delivery systemis configured to control delivery of the precursor of the material toeach station.
 3. The apparatus of claim 2, wherein: the controllerfurther comprises control logic for independently controlling precursordelivery to each station, and adjusting the deposition conditions in (c)comprises reducing or stopping flow of the precursor to the firststation.
 4. The apparatus of claim 1, further comprising a plasma sourceconfigured to independently form and maintain a plasma in each station,wherein: the controller further comprises control logic forindependently forming and maintaining a plasma in each station, and thedeposition conditions in (b) comprise exposing the first substrate andthe second substrate to the plasma.
 5. The apparatus of claim 4,wherein: the controller further comprises control logic forindependently controlling a plasma power level in each station, andadjusting the deposition conditions in (c) comprises reducing orstopping the exposure of the first substrate to the plasma.
 6. Theapparatus of claim 4, wherein: the controller further comprises controllogic for independently controlling a plasma time in each station, andadjusting the deposition conditions in (c) comprises reducing orstopping the exposure of the first substrate to the plasma.